Specimens of C. lepidus klauberi collected in the Southwestern USA and northern Mexico exhibited sexual color dimorphism. The basic body color was green for males and gray for females with both sexes possessing black or dark brown crossbands. This dichromatism probably evolved for background color-matching through natural selection influenced by predator pressure. The sexual basis of the dimorphism in body color may be the result of a sex-limited character that acts to balance the percentage of color morphs in the population, or it may function in intraspecific sex recognition if C. l. klauberi, a diurnally active snake, has redeveloped color vision.